It is super handy to have a calculator app built into your phone and ready to go whenever the need arises. For most people, the stock calculator app on their device will be adequate for basic calculations and day-to-day sums but functionality is usually limited to the mathematic fundamentals.

A calculator app from a third party has to stand out and offer something truly unique in order to warrant its download. Not only does it have to take on other apps in the same category on Google Play, but it also has to compete with the generally sufficient, preinstalled app on the phone already.

schoettler Software aims to motivate users to switch to CalcTape, its “Paper Tape Calculator” app, by making the arithmetic process visible.

With its eponymous ticker tape-like design, CalcTape sets out for you the calculation for you to see to in the top half of the screen — called the Scratchpad. Unlike most calculator apps, you can see the calculation history and even tap to edit any figures entered incorrectly. The best part about this design is that the final value is updated in real-time as you make amendments making it really easy to ensure you get complicated calculations completed correctly.

Another added benefit of seeing the calculation as you go is that you can add text notes to the Scratchpad. Simply tap next to any value to add a label or note to refer back to, and easily switch between text and numerical input to get back on with your calculations.

The bottom half of the screen shows your number pad, as you may expect from an app of this kind. Although it may not reveal it at first glance, the keypad has some special features hidden within. With the Pro version of CalcTape, unlocked via an in-app purchase, the user can benefit from multiple keyboards that can be customised to suit their needs. Each button’s size, position and function can be changed meaning you can create a custom keyboard that includes only the keys you need for your usage.

It is also possible to create a customer function button that can be programmed for a specific use case. Some preset examples include the addition and subtraction of tax, but you can create your own buttons for additions, subtractions, multiplications, divisions or percentage calculations. This is a really useful feature and makes completing common or specific calculations as easy as pressing one button once you have it set up.

There’s also an easily accessible copy to clipboard function that makes it simple and easy to take figures out of the app for use in other places.

While in the free version you can have your Scratchpad for ongoing calculations, the Pro version enables you to save calculations for later. This is something that sets CalcTape apart and enables you to keep a log of recent calculations for future reference or for an ongoing document of sums.

Where CalcTape succeeds in function, it lacks a little in form. The app’s design is fairly bland — although I’m not sure of many calculator apps that have particularly exciting designs. There are a few ways to make the app your own by customizing font size and line colour or by using one of the few themes included, but the design itself is a little uninspiring and can feel overly complex in its menus — a few too many taps and long presses required to make changes. Fortunately, there is a user guide linked within the app’s settings if you need guidance. CalcTape is also not a scientific calculator — by design — so look elsewhere if this is what you need.

If you are frustrated with the basic calculator app on your device and want an alternative way to manage your mobile mathematic matters, CalcTape is different enough to earn a try out. The ability to see your calculations, make edits on the fly and add notes to refer back to make CalcTape a unique offering. The, plus the customization options, the ability to save calculation documents and program your own function buttons give CalcTape some added control for mobile calculator power users.

Adam is Reviews Editor for PhoneDog, Android and Me and Today's iPhone. A Media and Communications graduate from Newcastle University in the UK, Adam is a Bradford City FC fanatic and self-confessed tech-nerd. You can follow him on Twitter: @adamoram.